[#4] Create SafeProtcolMediator contract

contracts/SafeProtocolMediator.sol

@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: LGPL-3.0-only
+pragma solidity ^0.8.18;
+import {ISafeProtocolMediator} from "./interfaces/Mediator.sol";
+import {ISafe} from "./interfaces/Accounts.sol";
+import "./DataTypes.sol";
+
+/**
+ * @title
+ * @notice
+ */
+contract SafeProtocolMediator is ISafeProtocolMediator {
+    /**
+     * @notice TODO
+     * @param safe TODO
+     * @param transaction TODO
+     * @return success TODO
+     * @return data TODO
+     */
+    function executeTransaction(
+        ISafe safe,
+        SafeTransaction calldata transaction
+    ) external view override returns (bool success, bytes memory data) {}
+
+    /**
+     * @notice TODO
+     * @param safe TODO
+     * @param rootAccess TODO
+     * @return success TODO
+     * @return data TODO
+     */
+    function executeRootAccess(
+        ISafe safe,
+        SafeRootAccess calldata rootAccess
+    ) external view override returns (bool success, bytes memory data) {}
+}

contracts/interfaces/Mediator.sol

@@ -13,12 +13,12 @@ interface ISafeProtocolMediator {
     /**
      * @notice TODO
      * @param safe Instance of a Safe account
-     * @param tx SafeTransaction instance containing payload information about the transaction
+     * @param transaction SafeTransaction instance containing payload information about the transaction
      * @return success boolean indicating status of execution.
      * @return data Arbitrary length bytes data returned upon the successful execution.
      *         Empty if the call failed.
      */
-    function executeTransaction(ISafe safe, SafeTransaction calldata tx) external view returns (bool success, bytes memory data);
+    function executeTransaction(ISafe safe, SafeTransaction calldata transaction) external view returns (bool success, bytes memory data);
 
     /**
      * @notice TODO